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Oversampling and questionnaire effects on precision and coverage of wealth. The new features of the French Wealth Survey wave 2010. Short presentation of the French Wealth Survey. Exists since 1986, a wave conducted every 6 years Aims at measuring households’ wealth and indebtedness
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Oversampling and questionnaire effects on precision and coverage of wealth The new features of the French Wealth Survey wave 2010
Short presentation of the French Wealth Survey • Exists since 1986, a wave conducted every 6 years • Aims at measuring households’ wealth and indebtedness • Fed with the experience accumulated along 20+ years, also with other surveys (in particular the SCF in the US) • In 2010, the French Wealth Survey is included in the Household Finance and Consumption Survey (HFCS)
The new features of the French Wealth Survey 2010 • Enlargement of the field and the concept • Oversampling of the wealthy • Questionnaire strategy • Imputation strategy
Effect of the oversampling - counterfactual • Using the design effects, it is possible to compute how high would have been the precision of a given estimator without oversampling • The idea behind: focus on those strata that contribute mostly to increase the precision of the estimator • This basic method provides a tool to arbitrate between gain of precision and interrogation costs • For example, the variance for the gross wealth mean would have been 48% higher in 2010 without oversampling
Conclusion • Enlargement of the field is a desirable option per se • Oversampling had a positive effect on the precision of the estimates – and probably also on the coverage rate • Both innovations in questionnaire and imputation strategies had a positive effect on the coverage effects and come alongside with the oversampling innovation • Still it is not completely sufficient – but consists of interesting methodologies that can be more or less easily implemented